298 VII. ACIDS, AMIDES, ALDEHYDES AND HYDROCARBONS 



CH3 • (CH2)3 • CHCCaHs) • (CH2)2 • COOH > 



7-Ethyloctanoic acid 



HOOC(CH2)3-CH(C2H5)-(CH2)2-COOH 



7-Ethylsuberic acid 



CH3-(CH2)3-CH(C2H,)(CH2)3-COOH > CH3(CH2)3CH(C2H6)CH2COOH 



5-Ethylnonanoic acid /3-Ethylheptanoic acid 



CH3(CH2)3CH(C2H5)(CH2)4COOH > HOOC(CH2)3CH(C2H6)(CH2)2COOH 



€-Ethyldecanoic acid 7-Ethylsuberic acid 



When the methyldodecanoic acids were fed in cocoa fat, the dogs receiv- 

 ing 5-methyldodecanoic acid excreted 35% of the weight of ingested tri- 

 glyceride as fatty material in the urine, ^®~^^ which was almost equal to the 

 amount of ethyl-substituted acids excreted. Methylsebacic acid was also 

 found in the urine. Although Dziewiatkowski et alA* reported that a- 

 ethylbutyric and a-ethylcaproic acids were excreted largely unchanged as 

 the glucuronide by the dog, somewhat different evidence was presented 

 earher as to the fate of such compounds. Thus, Blum and Koppel,^'' on the 

 basis of experiments on dogs, reported the excretion of methylpropyl ke- 

 tone (CH3CH2 • CO • CH3) when /3-ethylbutyric acid was injected subcu- 

 taneously. It was also reported by Baer and Blum^^ that this acid gives 

 rise to acetoacetic acid when perfused through the liver. It has likewise 

 been reported that a-ethylbutyric acid results in the formation of urinary 

 acetone bodies in human subjects. However, Dziewiatkowski and co- 

 workers^^ were unable to find any evidence of the formation of ketone bodies 

 after a-ethylbutyric or a-ethylcaproic acids had been fed to rabbits or rats. 



In later work by Keil and Schiller," it was found that the propyl- 

 branched fatty acids, when fed in a 1 : 3 mixture with cocoa fat, were ex- 

 creted as partially metabolized end-products to the extent of 10 to 25% 

 of the material fed. However, the propyl-substituted compounds were 

 better utilized than were the ethyl-substituted ones. The following reac- 

 tions were shown to occur with some of the substituted acids : 



CH3-(CH2)2-CH(C3H7)-COOH * Excreted unchanged 



a-Propylpentanoic acid 



CH3-(CH2)3-CH(C2H5)-CH2-COOH > Excreted unchanged 



/3-Ethylheptanoic acid 



CH3 • ( CH2 )2 • CH( C3H7 ) • CH2 • COOH > Excreted unchanged 



/3-Propylhexanoic acid 



» L. Blum and M. Koppel, Ber., 44, 3576-3578 (1911). 



*i J. Baer and L. Blum, Naunyn-Schmiedeberg's Arch, expll. Pathol. Pharmakol., 55, 

 89-115(1906); 56,92-100(1907). 



" W. Keil and G. Schiller, Z. physiol. Chem., 282, 135-136, 137-142 (1947). 



